Absorbent article having low rigidity sections

ABSTRACT

The absorbent article includes a chassis, a crotch region, an absorbent body, and an elastic member arranged along a side edge in width direction of the crotch region. The oblong absorbent body arranged in the crotch region includes a first narrow width section, a second narrow width section, a center low rigidity section formed along a center line that halves the absorbent article in the width direction and a pair of lateral low rigidity sections provided at both sides of the center low rigidity section in the width direction with a substantially equal interval. Skin contacting face-side sheets and non-skin contacting face-side sheets  6  and  10  are arranged in the crotch region. The initial tensile strength of the skin contacting face-side sheets is lower than that of the non-skin contacting face-side sheets or that of the chassis  2.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No.11/952,258, filed Dec. 7, 2007, which claims the benefit of priorityfrom Japanese Patent Application No. 2006-331240, filed on Dec. 7, 2006,the entire content of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an absorbent article such as adisposable diaper.

2. Related Art

Conventionally, a disposable diaper has been known as an absorbentarticle that absorbs and retains excretory substance (urine, stool)discharged from a human body. The absorbent article includes, forexample, a top liquid-permeable sheet, a back liquid-impermeable sheet,and liquid-retentive absorbent body provided between the top sheet andthe back sheet. The disposable diaper as described above functions sothat, when being worn by a user, excretory substance (e.g., urine)discharged from the user is absorbed via the top liquid-permeable sheetand retained by the absorbent body and excretory substance is preventedby the back liquid-impermeable sheet from leaking to the exterior of theabsorbent article.

Disposable diapers have been designed in many ways with a purpose ofpreventing the leakage or retention of excretory substance (e.g.,stool). For example, a diaper has been provided in which a top face anda back face of an absorption layer includes grooves along thelongitudinal direction of the absorption layer (see Japanese Patent No.3616077, hereinafter referred to as “Patent Publication 1”). This groovealong the longitudinal direction disperses excretory substance in thelongitudinal direction.

Generally, excretory liquid such as urine is discharged to a centersection in the longitudinal direction of the absorbent body. Accordingto the diaper of Patent Publication 1, excretory liquid is guided by thegroove formed along the longitudinal direction.

Patent Publication 1 describes a groove for guiding excretory liquid toabsorbent body. However, Patent Publication 1 does not disclose at allthat a part of an absorbent body is deformed so as to be abutted with anexcretory part having a urethral meatus or anus. Patent Publication 1also does not disclose at all that a side edge of absorbent body is benttoward legs to suppress the leakage of excretory liquid.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide an absorbentarticle that is abutted to an excretory part of a human body when beingworn by a user and that is deformed to suppress the leakage of excretorysubstance.

The present inventors have completed the present invention bydiscovering that a function for preventing the leakage of excretoryliquid, such as urine, and absorption capability can be improved byproviding an absorbent body structured by a low rigidity section at acrotch region of an oblong diaper at which the absorbent body is bentand that is formed along a center line for halving the absorbent body totwo parts in the width direction and a pair of lateral low rigiditysections that are provided at both sides in the width direction of thecenter low rigidity section with a substantially equal interval so thatthe both sides edges in the width direction of the absorbent body havegathers for preventing the leakage.

According to a first aspect of the present invention, an absorbentarticle having a width and a length orthogonal to the width, including:a chassis having at least a front torso surrounding region and a reartorso surrounding region arranged along a longitudinal direction of theabsorbent article; a crotch region provided between the front torsosurrounding region and the rear torso surrounding region of the chassis;an oblong absorbent body extending from the front torso surroundingregion to the rear torso surrounding region along the longitudinaldirection; a torso opening section formed at one side when in a wearingmode; a pair of leg openings formed at another side when in the wearingmode; a skin-contacting face facing an inner face when in the wearingmode; a not-skin-contacting face facing an outer face when in thewearing mode; and an elastic member arranged along a side edge in thewidth direction of the crotch region constituting the leg opening, inwhich the absorbent body includes: a first narrow width section; asecond narrow width section arranged longitudinally spaced from thefirst narrow width section; a center low rigidity section formed along acenter line that halves the absorbent article in the width direction;and a pair of lateral low rigidity sections provided at both sides ofthe center low rigidity section in the width direction with asubstantially equal interval; in which the crotch region is structuredso that the skin-contacting face of the absorbent body has a skincontacting face-side sheet and the not-skin-contacting face has eitherone of a not-skin contacting face-side sheet and the chassis, and inwhich the skin contacting face-side sheet has, while in a stretchedstate, a lower initial tensile strength in the width direction than thatof either one of the not-skin contacting face-side sheet and thechassis.

According to a second aspect of the present invention, an absorbentarticle having a width and a length orthogonal to the width, including:a chassis having at least a front torso surrounding region and a reartorso surrounding region arranged along a longitudinal direction of theabsorbent article; a crotch region positioned between the front torsosurrounding region and the rear torso surrounding region in the chassis;an oblong absorbent body provided extending from the front torsosurrounding region to the rear torso surrounding region along thelongitudinal direction; a torso opening section formed at one side whenin a wearing mode; a pair of leg openings formed at another side when inthe wearing mode; a skin-contacting face facing an inner face when inthe wearing mode; a not-skin-contacting face facing an outer face whenin the wearing mode; and an elastic member arranged along a side edge inthe width direction of the crotch region constituting the leg openingabsorbent body, in which the absorbent body includes: a first narrowwidth section; a second narrow width section arranged longitudinallyspaced from the first narrow width section; a center low rigiditysection formed along a center line that halves the absorbent article inthe width direction; and a pair of lateral low rigidity sectionsprovided at both sides of the center low rigidity section in the widthdirection with a substantially equal interval; in which the crotchregion is structured so that the skin-contacting face of the absorbentbody has a skin contacting face-side sheet and the not-skin-contactingface has either one of the not-skin contacting face-side sheet and thechassis, and in which the length in the width direction of the skincontacting face-side sheet is longer than that of the absorbent body.

In a third aspect of the absorbent article as described in the first orsecond aspect of the present invention, the absorbent body furtherincludes a center absorbing section provided in the longitudinaldirection between the first narrow width section and the second narrowwidth section, and the center absorbing section is shaped so that bothedges in the width direction protrude more than the first narrow widthsection and the second narrow width section protrude to outer sides ofthe width direction, respectively.

In a fourth aspect of the absorbent article as described in the thirdaspect of the present invention, in which both side edges at outer sidesin the width direction of the absorbent body have a pair of stretchingsheets arranged along the longitudinal direction, and the respectivestretching sheets are arranged to extend over both ends of the centerabsorbing section in the longitudinal direction to outer sides in thelongitudinal direction and are arranged to extend over both ends in thewidth direction of the center absorbing section to outer sides in thewidth direction.

In a fifth aspect of the absorbent article as described in the fourthaspect of the present invention, further includes: a pair of sideregions arranged widthwise outside each of the a pair of lateral lowrigidity sections; and a pair of center regions arranged between thecenter low rigidity section and each of the pair of lateral low rigiditysections, the stretching sheet is provided to be superposed on the sideregion in the width direction.

According to a sixth aspect of the absorbent article as described in thefifth aspect of the present invention, in which in the wearing conditionof the absorbent article, the side region is bent so that an end of anouter side in the width direction of the side region is raised in thethickness direction of the absorbent body, and the center region is bentso that an end of an inner side in the width direction of the centerregion is raised in the thickness direction, the absorbent body isconsequently deformed to have a W-letter shaped cross section in thewidth direction of the center absorbing section.

According to a seventh aspect of the present invention, an absorbentbody used for an absorbent article is provided including: a first narrowwidth section; a second narrow width section arranged longitudinallyspaced from the first narrow width section of the absorbent article; acenter absorbing section arranged between the first narrow width sectionand the second narrow width section in the longitudinal direction; acenter low rigidity section that is formed along a center line thathalves the absorbent body in the width direction; and lateral lowrigidity sections provided at both sides of the center low rigiditysection in the width direction with a substantially equal interval; inwhich the first narrow width section and the second narrow width sectionhave therebetween, in the longitudinal direction, the center absorbingsection shaped so that both edges in the width direction protrude toouter sides in the width direction and become wider than the firstnarrow width section and the second narrow width section.

Thus, the present invention can provide an absorbent article with anabsorbent body which is brought into contact with excretory part of thebody during wearing and which deforms to inhibit a leakage of dischargedmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a disposable diaper of the presentinvention.

FIG. 2 is a development view illustrating a developed disposable diaperaccording to an embodiment of the present invention.

FIG. 3 is an exploded view illustrating the disposable diaper accordingto an embodiment of the present invention.

FIG. 4A is a front view illustrating an absorbent body of the disposablediaper according to an embodiment of the present invention.

FIG. 4B is a cross-sectional view taken along X-X in FIG. 4A.

FIG. 5 is a cross-sectional view taken along X-X in FIG. 2.

FIG. 6 illustrates that the disposable diaper according to the presentembodiment is deformed.

FIG. 7 illustrates that the disposable diaper which is deformedaccording to the present embodiment.

FIG. 8 illustrates that the disposable diaper which is deformedaccording to the present embodiment.

FIG. 9 is a development view illustrating a disposable diaper accordingto another embodiment in a developed status.

FIG. 10 is an exploded view illustrating the disposable diaper accordingto another embodiment.

FIG. 11 is a cross-sectional view taken along X-X in FIG. 9.

FIG. 12 illustrates that the disposable diaper which is deformedaccording to another embodiment.

FIG. 13 illustrates that the disposable diaper which is deformedaccording to another embodiment.

FIG. 14 illustrates that the disposable diaper which is deformedaccording to another embodiment.

FIG. 15 illustrates a variation of the disposable diaper according tothe present embodiment.

FIG. 16 is a schematic view illustrating a relation between absorbentbody and a stretch sheet in the disposable diaper of another embodiment.

FIG. 17 illustrates a variation of the disposable diaper according toanother embodiment.

FIG. 18A illustrates an example of the present invention.

FIG. 18B illustrates an example of the present invention.

FIG. 18C illustrates an example of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings. It is noted that embodiments of the presentinvention are not limited to the following embodiments and the technicalscope of the present invention is not limited to these embodiments.

In this specification, it is assumed that an inner face of a disposablediaper 1 facing a body of a user is a skin-contacting face and an outerface opposite to the skin-contacting face is a not-skin-contacting face.This skin-contacting face is a top face at which a top sheet isprovided. The not-skin-contacting face is a back face. In thisspecification, the center line halving an absorbent body in thelongitudinal direction in a developed diaper is assumed as an inner sideand a width direction orthogonal to this longitudinal direction that isaway from the center and at which a diaper edge is arranged is assumedas an outer side.

In this embodiment, a pants-type disposable diaper will be mainlydescribed in which a front torso surrounding region and a rear torsosurrounding region are joined at a predetermined joint section to form atorso opening and a pair of leg openings. However, the present inventionis not limited to this type of disposable diaper. For example, theinvention also may be applied to a development-type disposable diaperthat can be worn by a used by attaching a front torso surrounding regionwith a rear torso surrounding region by an attaching member or the like.For example, the invention also may be applied to a pants-typedisposable diaper in which predetermined joint sections of a front torsosurrounding region and a rear torso surrounding region of a pants-typedisposable diaper are attached by a re-attachable attaching member(e.g., hook and loop fastener) as used in a development-type disposablediaper so that the pants-type disposable diaper can be unattacheddespite the pants-type structure and the pants-type disposable diapercan be developed and reattached.

In this embodiment, the term “wearing stage” means a status in which anabsorbent article can be worn by a user or a period just after theabsorbent article is worn by a user. For example, in the case of apants-type diaper, the term “wearing stage” means that predeterminedpositions are joined and the diaper is worn by a user to provide apants-like shape (so-called wearing mode). The term “wearing condition”means a condition after the diaper is worn by a user.

FIG. 1 is a perspective view illustrating a disposable diaper accordingto a first embodiment. FIG. 2 is a development view illustrating adeveloped disposable diaper according to the first embodiment. FIG. 3 isan exploded view illustrating the disposable diaper according to thefirst embodiment. FIG. 4A is a front view illustrating an absorbent bodyof the disposable diaper according to the first embodiment. FIG. 4B is across-sectional view taken along X-X in FIG. 4A. FIG. 5 is across-sectional view taken along X-X in FIG. 2. FIG. 6 illustrates thatthe disposable diaper according to the first embodiment is attached to auser and a force is applied to a crotch region and the crotch region isdeformed. FIG. 7 illustrates a further deformed crotch region after thestatus shown in FIG. 6. FIG. 8 illustrates a further deformed crotchregion after the status shown in FIG. 7 in which the absorbent body isbent to have a W-letter shape. FIG. 9 is a development view illustratinga disposable diaper according to a second embodiment in a developedstatus. FIG. 10 is an exploded view illustrating the disposable diaperaccording to the second embodiment. FIG. 11 is a cross-sectional viewtaken along X-X in FIG. 9. FIG. 12 illustrates that the disposablediaper according to the second embodiment is attached to a user and aforce is applied to a crotch region and the crotch region is deformed.FIG. 13 illustrates a further deformed crotch region after the statusshown in FIG. 12. FIG. 14 illustrates a further deformed crotch regionafter the status shown in FIG. 13 in which absorbent body is bent tohave a W-letter shape. FIG. 15 is a first modified embodiment of thedisposable diaper according to the first embodiment in which askin-contacting face sheet is loosened. FIG. 16 is a schematic viewillustrating a relation between absorbent body and a stretch sheet inthe disposable diaper of the second embodiment. FIG. 17 illustrates anot-skin-contacting face of the absorbent body entirely covered by thestretch sheet of the disposable diaper according to the secondembodiment. FIG. 18A illustrates a disposable diaper according to afirst example having a W-letter shape of a favorable cross section. FIG.18B illustrates a disposable diaper according to a second comparativeexample having no W-letter cross section. FIG. 18C illustrates adisposable diaper 1 having a W-letter cross section has anexcessively-high height toward an excretory part.

1. First Embodiment 1.1. Entire Structure

The entire structure of a disposable diaper as an example of theabsorbent article of the present invention is explained referring toFIGS. 1 to 4A. As shown in FIG. 1 and FIG. 2, the disposable diaper 1includes: a chassis 2 that forms an outer shape thereof and that has afront torso surrounding region 21 and a rear torso surrounding region22; a crotch region 23 positioned at a position corresponding to acrotch section of a user; and an absorbent body 4 that extends from thefront torso surrounding region of the chassis 2 to the rear torsosurrounding region along the longitudinal direction.

Also, as shown in FIG. 3, the disposable diaper 1 includes an elasticmember 7 that is provided at a crotch region 23. The elastic member 7forms a leakage preventing gather 40. Additionally, on a skin-contactingface of an absorbent body core 4 a, a cover sheet 4 b and a top sheet 3are arranged sequentially constituting a skin-contacting face sheetaccording to the present invention. On a non-skin-contacting face of anabsorbent body core 4 a, a back sheet 6 is arranged constituting anon-skin-contacting face sheet according to the present invention.

As shown in FIG. 4A, the absorbent core 4 a of the substantiallyrectangular absorbent body 4 arranged on the crotch 23 includes: a firstnarrow width section 31; a second narrow width section 32; a center lowrigidity section 35 on a center line CL equally dividing the disposablediaper 1 in the width direction; and a pair of lateral low rigiditysections 36 which is formed on both sides in the width direction of thecenter low rigidity section at substantially regular intervals.

1.2. Chassis

As shown in FIG. 1 or FIG. 2, the chassis 2 includes joint sections 24at which side edges of the front torso surrounding region 21 and therear torso surrounding region 22 are partially joined to each other. Inother words, the front torso surrounding region 21 is joined to the reartorso surrounding region 22 by intermittently joining the joint sections24 a and 24 a′ of the front torso surrounding region 21 to the jointsections 24 b and 24 b′ of the rear torso surrounding region 22 byultrasonic sealing for example. As a result, the chassis 2 is formed tohave a pants-like shape. The chassis 2 partially includes threadlikeelastic members 26 extending in the width direction to have apredetermined interval thereamong in the longitudinal direction. Thecrotch region 23 is composed of a stretching sheet.

1.3 Absorbent Body

1.3.1. Narrow Width Section

As shown in FIG. 3, the absorbent body 4 is substantially rectangularand composed of the absorbent core 4 a and the liquid-permeable coversheet 4 b covering the absorbent core 4 a. As shown in FIG. 4A, theabsorbent core 4 a has an oblong shape including a straight line havinga predetermined length along which side edges 53 a and 54 a extend fromthe front edge 50 of absorbent core 4 a in the longitudinal direction;the first concave section continuing from this straight line to protrudeto the inner side in the width direction; a convex section continuingfrom this first concave section to protrude to the outer side in thewidth direction; the second concave section continuing from this convexsection to protrude to the inner side in the width direction; and astraight line having a predetermined length continuing from this secondconcave section to extend in the longitudinal direction. This firstconcave part corresponds to the first narrow width section 31 and thesecond concave part corresponds to the second narrow width section 32.

The center absorbing section 39 has side regions 34 extending from thelateral low rigidity sections 36 to the outer sides of the absorbentbody 4 in the width direction to reach the side edges 53 b and 54 b; andthe center region 33 extending from the center low rigidity section 35to the lateral low rigidity section 36. Specifically, the centerabsorbing section 39 includes the center regions 33 provided at thecenter part in the width direction to sandwich the center low rigiditysection 35; and the side region 34 provided at the outer parts in thewidth direction and provided at the outer sides of the lateral lowrigidity section 36.

The “narrow width section” includes the first narrow width section 31and the second narrow width section 32. The term “narrow(er) width”means a part that has a narrower width than those of other parts of theabsorbent body. The first narrow width section 31 and the second narrowwidth section 32 are formed by gradually reducing the width from thefront torso surrounding region-side absorbing section 37 or the reartorso surrounding region-side absorbing section 38 of the absorbent body4 toward the center absorbing section 39.

1.3.2. Center Absorbing Section

The absorbent body 4 includes the center absorbing section 39 at thecenter in the longitudinal direction. The center absorbing section 39 isa part of the absorbent body 4 arranged in the crotch 23.

The outer edges 53 b and 54 b of the center absorbing section 39protrude to outer sides in the width direction and being wider than thefirst narrow width section 31 and the second narrow width section 32,and the outer edges thereof in the width direction are formed instraight lines. Thus the center absorbing section 39 has, at the fronttorso surrounding region side, the front torso surrounding region-sideabsorbing section 37 and has, at the rear torso surrounding region-side,the rear torso surrounding region-side absorbing section 38. The centerabsorbing section 39 has a length in the width direction for an adult of55 to 225 mm. And the absorbent body 4 preferably has a length in thelongitudinal direction of 50 mm to 300 mm. The reason is that the centerabsorbing section 39 having an excessively-large size causes anuncomfortable feeling or stiff feeling when the disposable diaper 1 isworn by a user while the center absorbing section 39 having anexcessively-small size cannot satisfy a required absorption performance.

Outer edges 54 b and 53 b at the side regions 34 are preferably shapedto have a straight line along the longitudinal direction. However, thepresent invention is not limited to this. For example, the outer edges54 b and 53 b also may be shaped to have a semicircular shape drawing agentle curve. The center absorbing section 39 is a part that isdeformed, when the disposable diaper 1 is worn by a user, to have aW-letter shape as described later.

1.3.3. Center Low Rigidity Section

The center low rigidity section 35 is shaped to have a straight linealong the center line CL along which the absorbent body core 4 a ishalved in the width direction. The center low rigidity section 35 may bea region having a low rigidity at which the absorbent body 4 is bent.For example, the center low rigidity section 35 may be a region having athin thickness, a low basis weight portion, a low density portion, aregion including a great number of small holes, or a region in whichabsorbent body has no basis weight.

The center low rigidity section 35 preferably has a length in thelongitudinal direction of 100 mm or more and more preferably of 200 mmto 450 mm for example. The center low rigidity section 35 has a lengthin the width direction of 5 mm to 15 mm for example. The center lowrigidity section 35 preferably has a length in the width directionwithin a range of 50% or less of the length of the absorbent body 4 inthe center absorbing section 39 in the width direction and has a lengthmore preferably in a range from 7 mm to 12 mm.

As shown in FIG. 5, the absorbent body 4 is obtained by covering theabsorbent core 4 a by the cover sheet 4 b. The back face of theabsorbent body 4 is adhered with a back sheet. The center low rigiditysection 35 is formed in a straight line along the center line CL atwhich the absorbent body 4 is halved in the width direction. An area inthe vicinity of the center low rigidity section 35 is preferably notjoined with the back sheet 6. The absorbent body 4 is structured so thatan area in the vicinity of a side region 34 of the absorbent body 4(which will be described later) is adhered to the back sheet 6 by a pairof adhesion sections 5. The respective adhesion sections 5 arepreferably spaced with a distance of 10 mm to 60 mm.

1.3.4. Lateral Low Rigidity Section

The lateral low rigidity sections 36 are formed to extend in the centerabsorbing section 39 in the longitudinal direction. The lateral lowrigidity sections 36 are formed at both sides of the center low rigiditysection 35 in the width direction. Specifically, the center absorbingsection 39 includes the two lateral low rigidity sections 36 thatsandwich the center low rigidity section 35. The lateral low rigiditysections 36 are formed to have a shorter length in the longitudinaldirection than that of the center low rigidity section 35. The laterallow rigidity sections 36 are a space as in the center low rigiditysection 35. In other words, the lateral low rigidity sections 36 areslits. The lateral low rigidity sections 36 may be, as in theabove-described center low rigidity section 35, a region having lowrigidity at which the absorbent body 4 can be bent. For example, thelateral low rigidity sections 36 may be a region having a thinthickness, a low basis weight portion, a low density portion or a regionincluding a great number of small holes.

The lateral low rigidity section preferably has a width in a range from3 mm to 15 mm and more preferably in a range from 5 mm to 10 mm. Thelateral low rigidity section preferably has a length in a range from 45mm to 215 mm and more preferably in a range from 55 mm to 150 mm. Awidth narrower than 3 mm causes an insufficient bending margin requiredfor the absorbent body to be bent to cause some cases in which theabsorbent body cannot be bent in a regular manner. For example, in orderto bend an absorbent body having a thickness of 3 mm by 180 degrees, alow rigidity section for the absorbent body must have a width of 6 mm,which is two times longer than 3 mm. A width of 15 mm or more may hinderthe absorbability of the crotch section.

The total sum of an area of the center low rigidity section 35 and anarea of the lateral low rigidity sections 36 is preferably 50% or lessof the total sum of the area of the center absorbing section 39. Whenthe total sum of an area of the center low rigidity section 35 and anarea of the lateral low rigidity sections 36 is higher than 50% of thetotal sum of the area of the center absorbing section 39, theabsorbability may decline to cause the leakage of excretory substance,which is not preferred.

The lateral low rigidity sections 36 functions to guide the deformationat the center absorbing section 39 in the thickness direction and alsofunctions as a region at which the center region 33 and the side region34 are bent during the deformation (which will be described later).

1.3.5. Side Region

The side regions 34 preferably have a length in the width direction in arange from 10 mm to 45 mm. The side regions 34 are a region that isdeformed, in the wearing condition of the disposable diaper 1, so thatends of outer sides in the width direction of the respective sideregions 34 are raised in the thickness direction. Specifically, the sideregions 34 are deformed at the lateral low rigidity sections 36 that areformed at the inner sides in the width direction of the side regions 34.

1.3.6. Center Region

The center region 33 preferably has a length in the width direction in arange from 10 mm to 45 mm. A ratio between the length of the side region34 (which will be described later) and the length in the width directionof the center region 33 is preferably within a range as described below.

Side region 34: center region 33=35 to 65:65 to 35

The center regions 33 is a region at which, in the wearing condition ofthe disposable diaper 1, ends at the inner sides in the width directionof the respective center regions 33 are deformed so that the ends areraised in the thickness direction. Specifically, the center regions 33is deformed so that the center regions 33 are bent at the center lowrigidity section 35 formed at one side in the width direction of thecenter regions 33 and at the lateral low rigidity section 36 formed atthe other side in the width direction of the center regions 33. The term“thickness direction” means a direction along the thickness of anabsorbent body prior to the deformation as described above.

1.3.8. Leakage Preventing Gather

As shown in FIG. 3, the leakage preventing gather 40 including theelastic member 7 is arranged along the side edge in the width directionof the crotch region 23. As shown in FIG. 5, the leakage preventinggather 40 is provided at the side edge of the outer side in the widthdirection of the absorbent body 4 along the longitudinal direction ofthe absorbent body 4.

The leakage preventing gather 40 is prepared in the manner as describedbelow. First, the side sheet 9 is provided between the absorbent body 4and the back sheet 6. The side sheet 9 sandwiches the side film 8 and atleast one elastic member 7 in a tensile status to cover the side film 8and the elastic members 7. Next, as shown in FIG. 5, the side sheet 9 isfolded into two parts so that the crease-side is provided at the outerside, and the inner side includes one end and the other end of the sidesheet 9. Then, the one end abutted to the back sheet 6 and the other endabutted to the absorbent body 4 are fixed at the adhesion section 5 byhot melt adhesive agent or the like so that the side sheet 9 issandwiched by the absorbent body 4 and the back sheet 6. As a result,the leakage preventing gather 40 is prepared.

Then, the elastic member 7 in the leakage preventing gather 40 isstretchable to raise the leakage preventing gather toward theskin-contacting face. The raised leakage preventing gather 40 functions,in the crotch of a user, to fill a gap between the absorbent body 4 andthe crotch to prevent excretory substance from leaking from the gap.

The side edge of the leakage preventing gather 40 including the elasticmember 7 is deformed, in order to maintain the condition in which thediaper is abutted to groins of a user's body, so that the side edges ofthe crotch region 23 are raised to the user's body while being pulled bythe leakage preventing gather 40. Specifically, the absorbent body 4provided at the crotch region 23 is also similarly deformed so that theside edges at the absorbent body 4 are raised to the user's body. Sincethe leakage preventing gather 40 is provided along the side edge in thewidth direction of the absorbent body 4, the absorbent body 4 isdeformed in the manner as described above. Specifically, the leakagepreventing gather 40 supports the deformation of the absorbent body 4 sothat the side edges of the absorbent body 4 are raised to the user'sbody.

1.3.8. Skin Contacting Face-Side Sheet

In the crotch region 23, the skin-contacting face of the absorbent core4 a has the cover sheet 4 b for covering the absorbent core 4 a. Thecover sheet 4 b consists of a liquid-permeable nonwoven cloth and isprovided so as to entirely cover the absorbent core 4 a. Specifically,the cover sheet 4 b is a sheet that is provided at the skin-contactingface of the absorbent core 4 a and is not fully adhered to the top faceof the absorbent core and thus is provided while being partiallyloosened and partially adhered.

The skin-contacting face of the cover sheet 4 b has the top sheet 3. Thetop sheet 3 is adhered to the cover sheet 4 b. As in the cover sheet 4b, the top sheet 3 consists of a liquid-permeable nonwoven cloth and canbe easily stretched. The top sheet 3 is also adhered to theskin-contacting face of the cover sheet 4 b and thus is provided whilebeing partially loosened and partially adhered as in the cover sheet 4b.

When the top sheet 3 is fixed by a chuck with an interval of 50 mm andis pulled with a tensile speed of 100 mm/minute, the top sheet 3 shows atensile strength of 0.58 N/50 mm when being stretched by 10%. When thenot-skin-contacting face sheet (which will be described later) is pulledunder the same conditions as those for the top sheet 3, thenot-skin-contacting face sheet 10 shows a tensile strength of 7.13 N/50mm. Thus, when compared with the not-skin-contacting face sheet 10, thetop sheet 3 can be easily stretched in the width direction of themanufacturing direction of the top sheet 3.

The tensile strength of the top sheet is measured by the followingprocedures. To measure the initial strength in the width direction of aproduct made therefrom, a test piece is obtained from the sheet of 100mm in the width direction and 50 mm in the lengthwise direction. Thetest piece is fixed by a chuck with an interval of 50 mm and is pulledwith a tensile speed of 100 mm/minute. The tensile strength in a case ofan expansion to 110% is read off and compared. An autograph-type tensiletest machine (AG-1kNI manufactured by Shimadzu Corporation) is used forthe tensile test.

As described above, the sheet provided at the skin-contacting face canbe easily stretched and is provided while being loosened. Thus, thedeformation of the absorbent body 4 in the thickness direction isprevented from being hindered. Specifically, the deformation of thecenter regions 33 in the center absorbing section 39 in which the centerregions 33 protrude from the center low rigidity section 35 in thethickness direction (to the skin-contacting face) is prevented frombeing hindered. As shown in FIG. 15, when the diaper is not worn by auser, the cover sheet 4 b or the like may be significantly loosened.Specifically, the length of the cover sheet 4 b in the width directionis longer than that of the absorbent body 4 in the width direction andthe length in the width direction of the top sheet 3 as askin-contacting face sheet is longer than that of the absorbent body 4in the width direction. The cover sheet can thus be loosened at theskin-contacting face of the absorbent body 4, and the absorbent body 4is easier to bend into W-letter shape when an inward force is given inthe width direction.

1.3.9. Not-Skin Contacting Face-Side Sheet

In the crotch region 23, the not-skin-contacting face of the absorbentbody 4 has the liquid-impermeable back sheet 6. The back sheet 6consists of a breathable film sheet having a low stretching property andis adhered to the not-skin-contacting face of the absorbent body 4 whilebeing stretched.

The not-skin-contacting face of the back sheet 6 has the outer coveringsheet 10 that has a high initial tensile strength. The outer coveringsheet 10 is adhered to the back sheet 6 while being stretched.Specifically, the outer covering sheet 10 is provided at thenot-skin-contacting face at a part or the entirety in the centerabsorbing section 39 of a range from the center region 33 to the sideregion 34.

1.3.10. Modified Embodiment of Absorbent Body

Hereinafter, with reference to FIG. 6 to FIG. 8, the deformation of theabsorbent body 4 in the wearing condition will be described. As shown inFIG. 6, the disposable diaper 1 at the wearing stage is pulled to theupper side in FIG. 6 and receives a force to the inner side in the widthdirection from legs of a user. In other words, the crotch region 23 atthe wearing stage is deformed to have a shorter length in the widthdirection. As a result, both side edges at the absorbent body 4 arefirstly deformed so that the side edges are raised to the user's body inthe thickness direction.

Specifically, the respective side regions 34 in the center absorbingsection 39 are deformed so that ends at the outer sides in the widthdirection of the side regions 34 are raised at the respective laterallow rigidity sections 36 formed at the inner side in the width directiontoward the user's body in the thickness direction. As a result, theabsorbent body 4 is deformed to have a U-like cross section in thethickness direction, as shown in FIG. 6.

Next, when the disposable diaper 1 is further pulled to the upper side,the absorbent body 4 receives a further force from the user's legs tothe inner side in the width direction. In other words, the crotch region23 is deformed to have a further shorter length in the width direction.As a result, the center section in the absorbent body 4 is deformed soas to protrude to the user's body in the thickness direction.

Specifically, in order to allow the center low rigidity section 35 inthe center absorbing section 39 to protrude to the user's body in thethickness direction, the respective center regions 33 are deformed sothat the respective center regions 33 are bent at the respective laterallow rigidity sections 36 formed at the outer sides in the widthdirection and the center low rigidity section 35 formed at the innerside in the width direction inner side. Specifically, the respectiveside edges at the center low rigidity section 35, which are at thecenter region 33 at one side and the other side in the width directionof the center low rigidity section 35, are deformed so as to be raisedto the user's body in the thickness direction. The reason why therespective side edges in the center regions 33 at the center lowrigidity section 35 are deformed so as to be raised to the user's bodyin the thickness direction is that the not-skin-contacting face of theabsorbent body 4 has a not-skin contacting face-side sheet such as theback sheet 6 having higher initial tensile strength than that of the topsheet 3 and the cover sheet 4 b which are sheets provided at theskin-contacting face in the absorbent body 4, and the outer coveringsheet 10 while the not-skin contacting face-side sheets being stretched.As a result, as shown in FIG. 7, the absorbent body 4 is deformed tohave a W-letter shaped cross section in the thickness direction.

When a user wearing the disposable diaper 1 has a standing posture, thecrotch region 23 is deformed to have a very short length in the widthdirection. As s result, the side edges of the absorbent body 4 aredeformed so as to be further raised to the user's body in the thicknessdirection and the center section of the absorbent body 4 are deformed tobe further raised to the user's body in the thickness direction.

Specifically, the respective side regions 34 in the center absorbingsection 39 are deformed so that the side regions 34 are bent at therespective lateral low rigidity sections 36 formed at the inner sides inthe width direction to allow the ends of the respective side regions 34at the outer sides in the width direction to be further raised to theuser's body in the thickness direction. Furthermore, in order toprotrude the center low rigidity section 35 in the center absorbingsection 39 to the user's body in the thickness direction, the respectivecenter regions 33 are deformed so that the center regions 33 are bent atthe respective lateral low rigidity sections 36 formed at the outersides in the width direction and the center low rigidity section 35formed at the inner side in the width direction. Specifically, therespective side edges at the center low rigidity section 35 at thecenter region 33 at one side and the other side in the width directionof the center low rigidity section 35 are deformed so as to be raised tothe user's body in the thickness direction. As a result, as shown inFIG. 8, the absorbent body 4 is deformed to have a more W-letter shapedcross section in the thickness direction.

When the diaper is worn by the user continuously, the leakage preventinggather 40 is maintained so that the side edges of the leakage preventinggather 40 including elastic member 7 are abutted with the groin regionof the user's body. Thus, as shown in FIG. 8, side edges in the centerabsorbing section 39 in the absorbent body 4 raised to the user's bodyin the thickness direction are maintained. When the user's legs areopened or closed in the wearing condition, a force is applied in thedirection of arrow A of FIG. 6 to cause the absorbent body 4 to bedeformed to have a W-letter shape. Thus, when the user stands up orwalks for example, the center section of the absorbent body 4 in thewidth direction protrudes to the user's body in the thickness directionand is abutted with an excretory part or the like.

As described above, the center absorbing section 39 in the absorbentbody 4 is deformed to have a W-letter shape. The center section of thecenter absorbing section 39 in the width direction is deformed toprotrude in the thickness direction and is abutted with an excretorypart of the user's body. Side edges of the center absorbing section 39at outer sides in the width direction are deformed to be raised in thethickness direction so that the edges can be abutted with the user'sbody. By the deformation of the absorbent body 4, the absorbent body 4can preferably absorb the excretory substance discharged from theexcretory part, for example, and can suppress the leakage of theexcretory substance from the user's body in the width direction.

According to the disposable diaper 1 of this embodiment, the absorbentbody 4 is deformed to have a W-letter shaped cross section in thethickness direction. Thus, a part in the vicinity of the center lowrigidity section 35 as a convex section in the W-letter shape is closeto or abutted to the excretory part of the user's body. Thus, thedisposable diaper 1 can immediately absorb the excretory substance fromthe excretory part can suppress excretory substance from streaming downon the skin of the user. Furthermore, the concave section in theW-letter shape formed by the center low rigidity section 35 and thelateral low rigidity section 36 stores excretory substance and also candisperse the excretory substance in the front-and-rear direction.Furthermore, the absorbent body 4 is deformed to have a W-letter shapeand thus the absorbent body 4 positioned close to the excretory part canhave a sufficient absorption area.

According to the disposable diaper 1 of this embodiment, the absorbentbody 4 is deformed to have a W-letter shaped cross section in thethickness direction. Thus, the crotch region 23 has a preferably shortlength in the width direction. Thus, feeling of pressure at the crotchsection can be reduced. Furthermore, in accordance with a movement of auser (e.g., opening or closing of legs), the absorbent body 4 stretchesin the width direction while changing the depth of the W-letter shape,thus providing an increased uncomfortable feeling.

2. Second Embodiment

The absorbent article of the second embodiment is an absorbent articlethat is different from that of the first embodiment in that the diaperof the first embodiment includes a stretch sheet. Hereinafter, the samecomponents and parts as those of the first embodiment are designated bythe same numerals and the corresponding descriptions similarly apply.

2.1. Stretch Sheet

As shown in FIG. 9 and FIG. 11, the disposable diaper 1 includes astretch sheet 11 extending from both side edges of the center absorbingsection 39 of the absorbent body 4 to the outer sides in the widthdirection. The stretch sheet 11 is not joined to the absorbent body 4.The stretch sheet is at least stretchable and elastic in thelongitudinal direction of the disposable diaper 1. The stretch sheet 11has a length adjusted to be shorter than the length of the back sheet 6superposed on the stretch sheet 11.

As shown in FIG. 16, the stretch sheet 11 is adhered to the back sheet 6and extends from a position 50 mm away in the width direction from thecenter S in the width direction of the lateral low rigidity section 36to a point 27.5 mm to the inner side in the width direction. Morepreferably, the stretch sheet 11 is arranged within 20 mm outward in thewidth direction and 10 mm inward in the width direction of the center S.In this case, a distance between the side edges 11 a of the stretchsheet is 70 mm to 110 mm.

It is noted that the absorbent body 4 and the stretch sheet 11 havetherebetween the leakage preventing gather 40 (which will be describedlater) and thus the absorbent body 4 is not directly joined to thestretch sheet 11. In FIG. 16, in order to simply illustrate the jointposition, the leakage preventing gather 40 is not shown. In an actualcase, the stretch sheet 11 is adhered to be sandwiched between the sidesheet 9 constituting the leakage preventing gather 40 and the back sheet6. The center of the lateral low rigidity section 36 in the widthdirection means, for example, a position 3.75 mm away from one end ofthe lateral low rigidity section 36, when the lateral low rigiditysection 36 has a width of 7.5 mm.

As shown in FIG. 16, when the adhesion section 5 adhered with theabsorbent body 4 and the back sheet 6 is assumed as a reference, theedge 5 a of the adhesion section 5 at the outer side in the widthdirection and the side edge 11 a of the stretch sheet 11 at the innerside in the width direction are adhered at a part at the outer side ofthe edge 5 a of the adhesion section in a range of 15 mm to 0 mm in thewidth direction or at a part at the inner side of the edge 5 a of theadhesion section in a range of 0 mm to 5 mm in the width direction. Morepreferably, the side edge 11 a is preferably away from the edge 5 a ofthe adhesion section by a distance of 10 mm to 5 mm. Specifically, thestretch sheet 11 and the adhesion section 5 may be separated from eachother or may be superposed. The side end 5 a of the adhesion section 5is at the outer side in the width direction from the lateral lowrigidity section 36 at which the diaper is bent.

The stretch sheet 11 has a plate-like shape having a predeterminedlength and is at least stretchable and elastic in the longitudinaldirection of the diaper. In the crotch region 23, the stretch sheet 11is provided at the outer side of the absorbent body 4 in the widthdirection and is not joined with the absorbent body 4. However, as shownin FIGS. 4A and 9, the absorbent body 4 has the longest width at thefront torso surrounding region-side absorbing section 37 and the reartorso surrounding region-side absorbing section 38 and has the shortestwidth at the first and second narrow width sections. Thus, the stretchsheet can be placed at both sides in the width direction of the centerabsorbing section 39 of the absorbent body 4 having a narrower width. Inthis case, the center absorbing section 39 has the convex side regions34 protruding in the width direction. However, the side region 34 andthe stretch sheet 11 may be superposed. It is noted that the stretchsheet 11 must not be adhered to the side region 34.

As shown in FIG. 16, width direction outer edges 11 b of the pair ofstretch sheets 11 are placed so as to go over both outer edges of theabsorbent body 4 in the width direction and to extend to outer sides inthe width direction. The stretch sheet 11 is adhered to the back sheet 6at both sides in the width direction of the back sheet 6 joined to theabsorbent body 4.

The stretch sheet 11 extends to the outer side in the width direction ofthe side edge of the absorbent body 4. In other words, the stretch sheet11 is placed at a face of the absorbent body 4 not abutted with a user'sskin so that the stretch sheet 11 protrudes from the absorbent body. Thewidth direction inner edge 11 a of the stretch sheet is superposed onthe side edge of the absorbent body 4. However, the width directionouter edge 11 b is not superposed on the absorbent body. The stretchsheet 11 is provided so as to further extend in the absorbent body 4longitudinal direction from both ends in the longitudinal direction ofthe center absorbing section 39.

As shown in FIG. 16 and FIGS. 18A to 18C, an interval between one widthdirection inner edge 11 a and the other width direction inner edge 11 aof the pair of stretch sheets 11 is preferably about 70 mm to 110 mm.When the interval is smaller than this range, the cross section issuppressed from having a W-letter shape. When the interval is largerthan this range, the stretch sheets for maintaining the W-letter shapeare excessively away from each other and thus the deformation of thecenter region cannot be controlled. Thus, the convex section formed fromthe center low rigidity section to extend to the user's body may have anexcessively-high height to the user's body.

By the arrangement as described above, the diaper can follow themovement of the user's legs and can easily stretch. Thus, the absorbentbody can be directly prevented from twisting or from being distorted dueto the movement of user's legs.

The stretch sheet 11 is adjusted to have a shorter length than that ofthe back sheet 6. Specifically, the stretch sheet 11 has preferably alength 20% or more shorter than the length of the back sheet. If thestretch sheet 11 does not have such a shorter length at all or has ashort length like that of the back sheet, the resultant absorbent bodyis planar or is abutted with the crotch section in an inverted V-likeshape to increase a width at which the absorbent body has a contact witha user's skin or to cause the absorbent body to be abutted to the innerthigh, thus causing the user to experience an uncomfortable feeling.

Although the tensile strength of the stretch sheet 11 is differentdepending on the basis weight or rigidity of the or an existence ornon-existence of a slit, when assuming that the crotch region has alength Y (i.e., the length of the back sheet in the crotch region), thestretch sheet 11 has a tensile strength of 0.5 N or more and 10 N orless and preferably a tensile strength in a range of 2 N to 7 N when thestretch sheet 11 is elongated to have a length of Y×95%. An excessivelyweak stress of the stretch sheet 11 prevents the side region 34 of theabsorbent body 4 from being supported from the lower side to fail toprovide a W-letter shape. An excessively strong stress of the stretchsheet 11 on the other hand causes a V-like shape or prevents the stretchsheet 11 from being sufficiently elongated to cause a gap between auser's skin and the absorbent body, causing a risk where excretorysubstance streams down the skin to leak.

The stretch sheet 11 preferably has the narrowest width of 10 mm or moreand the widest width of about 100 mm and the outer edge is cut tocorrespond to the shape of a leg opening of a crotch section. This shapecan allow a part corresponding to a complicated shape of a human body(e.g., crotch section, a part close to a groin) to have be abutted withthe body in a plane.

In this embodiment, the stretch sheet 11 is obtained by joining the backsheet 6 as an unstretching nonwoven cloth provided at the back face ofthe absorbent body with a stretchable and elastic nonwoven cloth in thelongitudinal direction of a resultant product while the components beingstretched. However, the stretch sheet 11 is not limited to this so longas the stretch sheet 11 has a plane-like shape of 10 mm or more and canbe stretchable and elastic in the longitudinal direction of the diaper.For example, the stretch sheet 11 also may be a single stretchingnonwoven cloth, a complex sheet of two layers or more including astretchable and elastic film or net, a plane-like member obtained byarranging a plurality of threadlike elastic members with a small pitchof 10 mm or less, or urethane foam. Alternatively, the entire crotchregion also may be provided by a stretching member and a part other thana stretchable and elastic crotch part also may be processed so that thispart is not stretchable or elastic.

2.2. Modified Embodiment of Stretch Sheet

Hereinafter, with reference to FIG. 12 to FIG. 14, the deformation ofthe absorbent body 4 in the wearing condition will be described. Asshown in FIG. 12, when the stretch sheet 11 is worn by a user, thestretch sheet 11 extends along the crotch to the inner thigh of theuser, while stretching in the longitudinal direction of the diaper. Asshown in FIG. 13, when the disposable diaper 1 is pulled up to thecrotch region, the stretch sheet 11 is abutted surface-to-surface to theinner thigh of the user. As shown in FIG. 14, when the disposable diaper1 is completely pulled up to the user's body and is placed at the crotchof the user's body without causing an uncomfortable feeling at thecrotch region 23, the width direction outer edge 11 b of the stretchsheet is attached so as to face the not-skin-contacting face in thethickness direction of the absorbent body.

The absorbent article according to the second embodiment also includesthe leakage preventing gather 40 as in the first embodiment. Thus, whenthe elastic member 7 of the leakage preventing gather 40 is stretched,the side region 34 of the absorbent body 4 is raised. The stretch sheet11 is pulled up so as to support the raised side region 34 by thenot-skin-contacting face. Thus, the side region 34 is stable to allowthe absorbent body 4 to be stably bent in the thickness direction.

By the structure as described above, when the disposable diaper 1 isworn by a user, the side region 34 of the absorbent body 4 is raised tosupport the absorbent body 4 to be bent to have a U-like shape.Furthermore, an upper end of the edge of the outer side in the widthdirection of stretch sheet 11 to the user's body is always retained soas to have a contact with a groin of the user. When the diaper is wornby a user, the stretch sheet 11 is abutted surface-to-surface with theinner thigh of the user to function to block the lateral leakage ofexcretory substance. Furthermore, the stretch sheet 11 is placed in thevicinity of the side region 34 of the absorbent body 4 and at a positionat which the W-letter shape is bent. Thus, even when the absorbent body4 deformed to have the W-letter cross section extends in the lateraldirection due to opening and closing of legs, the stretch sheet 11 isstretched to function to retain the deformed W-letter shape.

According to the disposable diaper 1 of this embodiment, the stretchsheet 11 is composed of a plane sheet of a width of 10 mm or more. Thus,the stretch sheet 11 can be abutted with a complicated shape of thecrotch region of the user, not in lines but surface-to-surfaceextensively, thus preventing an occurrence of a gap. In the wearingcondition, the stretch sheet 11 is abutted with the inner thigh so as tofill the gap caused between the inner thigh and the disposable diaper 1.Since the absorbent body 4 and the back sheet 6 have therebetween theleakage preventing gather 40, even when excretory substance leaks fromthe leakage preventing gather 40, the stretch sheet 11 abutted with theinner thigh in a plane can block the excretory substance. Furthermore,since the sheet having a width of 10 mm is joined to the outer edge ofthe back sheet 6, a user's leg can be prevented from touching the gatheror frill to provide a simpler appearance and to allow the diaper to beworn more comfortably, thus providing increased feeling of security.

First Modified Embodiment

As shown in FIG. 17, the stretch sheet 11 also functions as the backsheet 6, is adhered to the back face of the absorbent body 4, and canallow the width direction outer edge 11 b of the stretch sheet to extendto the outer side in the width direction of the absorbent body 4 as inthe above-described stretch sheet 11. A stretch sheet of the firstmodified embodiment may be adhered to the absorbent body 4 at the sameposition as that in the first embodiment. Specifically, a part in thevicinity of the center region 33 of the absorbent body 4 is not joinedto the absorbent body 4 and only a part in the vicinity of the sideregion 34 can be adhered to the absorbent body 4. As in the firstembodiment, the not-skin-contacting face sheet 10 is an unstretchingsheet. Thus, the center region 33 of the absorbent body 4 can protrudein the user's body direction. By the structure as described above, laborrequired for providing the back sheet 6 can be eliminated to reduce themanufacture steps. Furthermore, the manufacture cost of the back sheet 6also can be reduced.

3. Third Embodiment

An absorbent article of a third embodiment is different from that of thefirst embodiment in that a region having a thin thickness is formed as alow rigidity section. The region having a thin thickness is formed byreducing the thickness of the absorbent body. Specifically, the regionhaving a thin thickness is formed by reducing the basis weight to causethe low rigidity section to have a lower fiber density than those ofother parts of the absorbent body 4. The center low rigidity section 35and the lateral low rigidity section 36 may mainly composed of, forexample, pulp of natural fiber, or chemical fiber with a fiber length of1 mm to 10 mm for which a ratio of the pulp and pulp mass/(pulp and SAPmass) to the absorbent body mass is 45% to 100%. The pulp basis weightmay be in a range of 5 g/m2 to 200 g/m2 and is preferably 200 g/m2. Theregion having a thin thickness may have a thickness of 0.1 mm to 2.0 mm.On the other hand, with regards to the fiber density of a part otherthan the region having a thin thickness as the center low rigiditysection 35 and the lateral low rigidity section 36, in the case of pulphaving a fiber length of 1 mm to 10 mm, a ratio of the pulp mass/(pulpand SAP mass) to the absorbent body mass may be 45% to 65%. In thiscase, the pulp basis weight may be within a range of 50 g/m2 to 400 g/m2and the thickness may be within a range of 1.0 mm to 5.0 mm.

As described above, by reducing the basis weight so that the lowrigidity section can have a lower fiber density than those of otherregions of the absorbent body 4, the low rigidity section can have athinner thickness than those of other regions parts of the absorbentbody 4. Thus, the absorbent body 4 has lower rigidity. As a result, whenthe diaper is worn by a user and the diaper receives a force from theinner thigh of the user to the inner side of the user's body, theabsorbent body 4 is bent at the low rigidity section.

The third embodiment is the same as the first embodiment except for thatthe absorbent body 4 of the low rigidity section of the third embodimentis formed by the low rigidity section to have a thinner thickness thanthose of other regions of the absorbent body 4.

EXAMPLE

The following section will describe examples of the present invention.However, the examples are mere examples for favorable carrying out thepresent invention and do not limit the present invention in any way.

First Example

As shown in Table 1, widths of the side region 34 and the center region33 of the absorbent body 4 were changed to evaluate the wearing feelingand whether the absorbent body has a clear W-letter shaped cross sectionor not. An absorbent body in this evaluation was prepared in the manneras described below. First, high absorbance polymer (e.g.,polyacrylate-base or starch/acrylate-base one) including 80% or moreabsorbance polymer having a water absorption factor of 20 g/g or moreand a grain size of 100 to 800 μm and hydrophilic fiber (e.g., groundpulp fiber or rayon fiber) were prepared. Then, the high absorbancepolymer and the hydrophilic fiber were covered by the cover sheet 4 bthe cover sheet 4 b as a hydrophilic sheet obtained by subjectinghydrophobic fiber (e.g., polyolefin-based one, polyester-base one) to ahydrophilic processing. In a first example, the lateral low rigiditysection has a width of 7.5 mm and the center low rigidity section has awidth of 10 mm. The side region 34 and the center region 33 both have awidth of 23.8 mm. The absorbent body 4 of the first example has a totalwidth of 120.2 mm.

TABLE 1 First First Second Third Fourth Comparative Fifth ExampleExample Example Example Example Example Width A of 23.8 10 15 35 50 23.8Absorbent core Width B of 23.8 10 15 35 50 23.8 Absorbent core Side slit7.5 7.5 7.5 7.5 7.5 3 width Center 10 10 10 10 10 5 slit width Total120.2 65 85 165 225 106.2 width of absorbent body Wearing ∘ ∘ to Δ ∘ toΔ ∘ to Δ x ∘ to Δ feeling/W- letter shape Unit: mm ∘: Good Δ: Acceptablex: Poor

Second Example

A second example uses the same disposable diaper 1 as that of the firstexample except for that the disposable diaper of the first example isstructured so that the lateral low rigidity section has a width of 10 mmand the center low rigidity section has a width of 10 mm. Thus, theabsorbent body 4 had a total width of 65 mm.

Third Example

A third example uses the same disposable diaper 1 as that of the firstexample except for that the disposable diaper 1 of the third example isstructured so that the lateral low rigidity section has a width of 15 mmand the center low rigidity section has a width of 15 mm. Thus, theabsorbent body 4 had a total width of 85 mm.

Fourth Example

A fourth example uses the same disposable diaper 1 as that of the firstexample except for that the disposable diaper 1 of the fourth example isstructured so that the lateral low rigidity section has a width of 35 mmand the center low rigidity section has a width of 35 mm. Thus, theabsorbent body 4 had a total width of 165 mm.

First Comparative Example

A first comparative example uses the same disposable diaper 1 as that ofthe first example except for that the disposable diaper 1 of the firstcomparative example is structured so that the lateral low rigiditysection has a width of 50 mm and the center low rigidity section has awidth of 50 mm. Thus, the absorbent body 4 had a total width of 225 mm.

Fifth Example

A fifth example uses the same widths of the side region 34 and thecenter region 33 as those of the first example but is different in thatthe lateral low rigidity section 36 has a width of 3 mm and the centerlow rigidity section 35 has a width of 5 mm. Thus, the absorbent body 4had a total width of 106.2 mm.

Evaluation

In the case of the first comparative example, the side region 34 and thecenter region 33 had an excessively-wide width to cause a wide totalwidth of the absorbent body 4 to prevent the diaper from suiting thelateral width of the user's crotch portion. The cross section showed noW-letter shape. In the case of the third example and the fourth example,a slightly improved result was obtained. In the case of the secondexample, undesirable result was sometimes obtained. Although the widthsof the side region 34 and the center region 33 in a range from 15 mm to35 mm can provide a W-letter shape, it was found that a favorableW-letter shape could be obtained when the widths of the side region 34and the center region 33 were within a range of about 20 mm to about 25mm. In the case of the first example in which the side region 34 and thecenter region 33 had a width of 23.8 mm, the wearing feeling and theW-letter shape were both favorable. With regards to the width of theentire absorbent body, a width of 65 mm or less as shown in the secondexample is not sufficient to provide a W-letter shape at the crotchregion of the user. A width of 200 mm or more on the other handsignificantly exceeds the lateral width of the crotch of the user andthus cannot form a desired bent shape. A width from about 80 mm to about180 mm could provide a clear W-letter shape.

First Example

The disposable diaper according to the first example was prepared sothat one edge has a curved shape so as to suit the shape of a user's theleg as shown in FIG. 9 and FIG. 10 and the oblong stretch sheet 11having a shorter length in the longitudinal direction than that of theback sheet 6 of the disposable diaper 1 by 46% was used to prepare thedisposable diaper according to the second embodiment. Specifically, thelength of the back sheet 6 is 480 mm and the stretch sheet 11 is 260 mm.A nonwoven cloth was used that was composed of fibers of polyurethanehaving a basis weight of 14 g/m2 to 30 g/m2 and polypropylene having abasis weight of 17.5 g/m2 to 36 g/m2, and a ratio between polypropyleneand polyurethane was 40:60 to 50:50. A stretch sheet 11 is applied beingstretched to 180% to the longitudinal direction, having a length of 260mm.

The above stretch sheet was adhered, by a hot melt adhesive agent,between the back sheet 6 that was mainly composed of polyolefin-baseresin and that was composed of a resin film having a basis weight in arange of 10 g/m2 to 30 g/m2 and a side sheet of the leakage preventinggather that was composed of a water-shedding nonwoven cloth having abasis weight in a range of 10 g/m2 to 30 g/m2 and polyurethane elasticyarn of 470 to 940 detex. The pair of stretch sheets were adhered to beopposed to each other at both side edges of the crotch region of thedisposable diaper to have an equal distance to the center line CL thatextended in the longitudinal direction to halve the disposable diaper 1in the width direction.

The stretch sheet 11 of the first example was adhered so that one edgeat the inner side in the width direction of the center absorbing sectionwas separated from the other edge at the inner side in the widthdirection of by a distance of 90 mm.

Second Comparative Example

In the second comparative example, the stretch sheet was adhered betweenthe back sheet and the leakage preventing gather as in the first exampleembodiment. In the second comparative example, the stretch sheet wasadhered so that edges at the inner side in the width direction of a pairof stretch sheets were separated by a distance of 30 mm.

Third Comparative Example

In a third comparative example, the stretch sheet was adhered betweenthe back sheet and the leakage preventing gather as in the firstexample. In the third comparison example, the stretch sheet was adheredso that edges at the inner side in the width direction of a pair ofstretch sheets were separated by a distance of 130 mm.

Evaluation

The resultant disposable diapers of the second and third examples andthe second and third comparative examples were attached to a human modelthat had a crotch width of 40 mm and that was based on a 70 years oldwoman having an average figure. Then, these disposable diapers wereevaluated with regards to the shapes of the cross sections of the crotchregions. In the first example, the cross sections showed a clearW-letter shape. In the case of the second comparative example, adistance between a side edge in the width direction of a pair of stretchsheets and a side edge in the width direction of stretch sheet were tooshort and failed to provide a W-letter shape. In the case of the thirdcomparative example, the distance between a pair of stretch sheets andthe stretch sheet was too long. Thus, although a W-letter shape wasformed, a height of a convex section at the center of the W-letter shapeprotruding to the user's body was excessively high when compared withthat of first example. This may cause the user to experience anuncomfortable feeling. When the distance between the inner edge in thewidth direction of a pair of stretch sheets and the inner edge in thewidth direction of the stretch sheet was changed, a favorable W-lettershape was found when the distance was in a range of 70 mm to 110 mm.

First Example

As shown in Table 2, by changing a position at which the absorbent body4 was adhered to the surface of the back sheet 6, the positionalrelation with the stretch sheet was evaluated. In the case of the firstexample, there was a distance of 5 mm between the outer edge 5 a of theadhesion section 5 of the absorbent body 4 and the inner edge 11 a ofthe stretch sheet 11. The inner ends in the width direction of the pairof adhesion sections 5 were adhered at positions having an interval ofabout 40 mm therebetween. In Table 2, the term “distance” means adistance between the outer edge 5 a of the adhesion section of theabsorbent body and the inner edge 11 a of the stretch sheet. When theouter edge 5 a of the adhesion section 5 of the absorbent body 4 wasaway from the inner edge 11 a of the stretch sheet 11, the distance wasrepresented by a negative value. When the outer edge 5 a of the adhesionsection 5 of the absorbent body 4 was superposed with the inner edge 11a of the stretch sheet 11, the distance was represented by a positivevalue.

TABLE 2 Fourth Fifth Comparative Comparative Sixth Seventh First EighthNinth Example Example Example Example Example Example Example Distance−45 −35 −25 −15 −5 +5 +15 (mm) W- x x Δ ∘ ∘ ∘ Δ letter shape/ wearingfeeling ∘: Good and unstable shape Δ: Acceptable x: Poor and unstableshape

Sixth Example

A sixth example is the same as the first example except that a distanceof 25 mm was provided between the outer edge 5 a of the adhesion section5 of the absorbent body 4 and the inner edge 11 a of the stretch sheet11.

Seventh Example

A seventh example is the same as the first example except that adistance of 15 mm was provided between the outer edge 5 a of theadhesion section 5 of the absorbent body 4 and the inner edge 11 a ofthe stretch sheet 11.

Eighth Example

An eighth example is the same as the first example except that the outeredge 5 a of the adhesion section 5 of the absorbent body 4 wassuperposed on the inner edge 11 a of the stretch sheet 11 by 5 mm.

Ninth Example

A ninth example is the same as the first example except for that theouter edge 5 a of the adhesion section 5 of the absorbent body 4 wassuperposed on the inner edge 11 a of the stretch sheet 11 by 15 mm.

Fourth Comparative Example

A fourth comparative example is the same as the first example except forthat the outer edge 5 a of the adhesion section 5 of the absorbent body4 was separated the inner edge 11 a of the stretch sheet 11 by 45 mm.

Fifth Comparative Example

A fifth comparative example is the same as first example except for thatthe outer edge 5 a of the adhesion section 5 of the absorbent body 4 wasseparated the inner edge 11 a of the stretch sheet 11 by 35 mm.

Evaluation

In the case of the fourth and fifth comparative examples, the outer edge5 a of the adhesion section 5 of the absorbent body 4 was excessivelyseparated from the inner edge 11 a of the stretch sheet 11 to cause poorshape stability. In the case of the sixth example, the outer edge 5 a ofthe adhesion section 5 of the absorbent body 4 was separated from theinner edge 11 a of the stretch sheet 11 by a distance of 25 mm. In thecase of the ninth example, the outer edge 5 a of the adhesion section 5of the absorbent body 4 was superposed on the inner edge 11 a of thestretch sheet 11 by 15 mm. The sixth and ninth examples showed aslightly stable shape. The first, seventh and eighth examples showedfavorable shape stability. In conclusion, the outer edge 5 a of theadhesion section 5 of the absorbent body 4 is preferably superposed onthe inner edge 11 a of the stretch sheet 11 preferably by about 5 mm orthe outer edge 5 a is preferably separated from the inner edge 11 a byabout 15 mm. The distance between the outer edge 5 a and the inner edge11 a by about 5 mm of the first example was found to be more preferable.

4. The Respective Constituting Members

The following section will describe the respective constituting membersof a disposable diaper.

4.1. Chassis

The chassis 2 constitutes the outer shape of the disposable diaper 1.The chassis 2 may be provided by one sheet-like member or may beprovided by adhering a plurality of sheet-like members. It is noted thatthe disposable diaper 1 in this embodiment includes the stretchablechassis 2 having the front torso surrounding region 21 and the reartorso surrounding region 22 and the unstretching crotch region 23positioned between the front torso surrounding region 21 and the reartorso surrounding region 22. The chassis 2 and the crotch region 23 inthe longitudinal direction are joined with the top sheet 3, theabsorbent body 4, and the back sheet 6. However, the present inventionis not limited to this so long as the diaper is structured so that asheet in the crotch region facing a not-skin-contacting face from theabsorbent body has higher initial tensile strength than that of a sheeton a skin-contacting face. For example, another structure also may beused in which the front torso surrounding region 21 of the chassis 2 iscontinued from the crotch region 23 positioned between the rear torsosurrounding region 22 and the front torso surrounding region 21 and therear torso surrounding region 22 and only the crotch region is theunstretching one.

The chassis 2 is preferably made of material that is breathable, thathas strength to prevent the diaper from being damaged even when thediaper worn by a user receives a load due to compression, distortion, orfriction for example, and that does not stimulate the user's skin forexample. The material may be a breathable sheet-like member (e.g.,nonwoven cloth, perforated plastic sheet).

4.2. Top Sheet

When the diaper is worn by a user, the top sheet 3 as a skin-contactingsheet faces the user's body and is abutted with an excretory part. Thetop sheet 3 may be entirely or partially liquid-permeable.Alternatively, the top sheet 3 may be composed of one sheet-like memberor may be composed of a plurality of sheet-like members.

The top sheet 3 is preferably made of material that has strength toprevent the diaper from being damaged even when the diaper worn by auser receives a load due to compression, distortion, or friction forexample and that does not stimulate the user's skin. For example, thematerial may be a liquid-permeable sheet-like member such as a wovencloth, a nonwoven cloth, or a perforated plastic sheet.

4.3. Absorbent Body

The absorbent body 4 absorbs and retains discharged body fluid such asurine. The absorbent body 4 may have a structure obtained by mixinghighly absorbing polymer with a hydrophilic fiber to layer the materialor a structure in which highly absorbing polymer is fixed to ahydrophilic sheet by hot melt adhesive agent for example. The highlyabsorbing polymer may be, for example, the one including 80% or moreabsorbability polymer (e.g., polyacrylate-base one, starch/acrylate-baseone) having a water absorption factor of 20 g/g or more and a grain sizeof 100 to 800 μm.

4.4. Back Sheet

The back sheet 6 may be, for example, a thermoplastic film mainlyincluding polyethylene (PE), polypropylene (PP) or the like, abreathable resin film, a sheet obtained by joining a nonwoven clothbased on the spun bond or the spun lace method or the like with abreathable resin film, or a plurality of layers based on SMS (spun bond,melt blow, and spun bond) for example. Preferably, the back sheet 6 is aresin film mainly including polyolefin-base resin with a basis weight of10 g/m2 to 30 g/m2 for example.

The backsheet 6 may be obtained by joining the not-skin-contacting faceof this back sheet 6 with a nonwoven cloth or the like. Thenot-skin-contacting face of the back sheet 6 joined with a nonwovencloth or the like is preferable because it provides an improved touch toa user's skin at the wearing stage for example. When the back sheet 6 isa film, the film may be preferably joined with a nonwoven cloth or thelike because it can prevent uncomfortable noise due to fiction of thefilm for example.

4.5. Elastic Member and Stretch Sheet

An elastic member may be composed of, for example, natural rubber orsynthetic rubber (e.g., styrene-butadiene, butadiene, isoprene). Thesheet-like elastic member 26 can be formed by a nonwoven cloth of foamedpolyurethane having a basis weight of 30 g/m2 to 80 g/m2 or mixed fiberof polyurethane of basis weight of 20 g/m2 to 70 g/m2 and polypropylenefor example.

4.6. Adhesive Agent

The top sheet 3 and the absorbent body 4 are adhered to the chassis 2 byhot melt adhesive agent. The top sheet 3 is adhered to the absorbentbody 4 by hot melt adhesive agent. It is noted that the joint is notlimited to the above hot melt adhesion and also may use, for example, acombination of heat sealing and ultrasonic sealing for example. Whilepreferred embodiments of the present invention have been described andillustrated above, it is to be understood that they are exemplary of theinvention and are not to be considered to be limiting. Additions,omissions, substitutions, and other modifications can be made theretowithout departing from the spirit or scope of the present invention.Accordingly, the invention is not to be considered to be limited by theforegoing description and is only limited by the scope of the appendedclaims.

What is claimed is:
 1. An absorbent article having a width and a lengthorthogonal to the width, comprising: a chassis having at least a fronttorso surrounding region and a rear torso surrounding region arrangedalong a longitudinal direction of the absorbent article; a crotch regionpositioned between the front torso surrounding region and the rear torsosurrounding region in the chassis; an oblong absorbent body providedextending from the front torso surrounding region to the rear torsosurrounding region along the longitudinal direction, the absorbent bodycomprising an absorbent core covered with a cover sheet; a pair ofstretchable sheets arranged at both outer side edges of the cover sheetwith respect to the width direction and extending in the longitudinaldirection, an outer edge of each of the stretchable sheets being formedto have an arch portion that recesses toward a center line of theabsorbent body at a center portion in the longitudinal direction of thestretchable sheets; a torso opening section formed at one side when in awearing mode; a pair of leg openings formed at another side when in thewearing mode; a skin-contacting face facing an inner face when in thewearing mode; a not-skin-contacting face facing an outer face when inthe wearing mode; and an elastic member arranged along a side edgeextending in a longitudinal direction of the crotch region constitutingthe leg opening, wherein the absorbent core includes: a first narrowwidth section; a second narrow width section arranged longitudinallyspaced from the first narrow width section; a center low rigiditysection formed along a center line that halves the absorbent article inthe width direction of the absorbent article; and a pair of lateral lowrigidity sections provided at both sides of the center low rigiditysection in the width direction of the absorbent article with asubstantially equal interval; wherein the cover sheet has at a skincontacting side a length in the width direction that is longer than alength of the absorbent core in the width direction so that the coversheet at the skin contacting side is loosened, and at the skincontacting side, the cover sheet is entirely free of joining with theabsorbent core from one end to another end in the width direction of theabsorbent core, and the stretchable sheet has a narrowest width at thearch portion, and a portion of the stretchable sheet that has thenarrowest width at the arch portion extends outward over the outer sideedge of the cover sheet at the arch portion, and the outer edge of thestretchable sheet extends over the outer side edge of the cover sheetalong an entire length of the stretchable sheet in the longitudinaldirection of the absorbent core, the absorbent article is a diaper foran adult.
 2. The absorbent article according to claim 1, wherein theabsorbent core further comprises a center absorbing section provided inthe longitudinal direction between the first narrow width section andthe second narrow width section, the center absorbing section is shapedso that both edges in the width direction protrude more than the firstnarrow width section and the second narrow width section protrude toouter sides of the width direction, respectively.
 3. The absorbentarticle according to claim 2, wherein the center absorbing section has alength in the width direction of 55 to 225 mm.
 4. The absorbent articleaccording to claim 1, further comprises a pair of side regions arrangedwidthwise outside each of the pair of lateral low rigidity sections anda pair of center regions arranged between the center low rigiditysection and each of the pair of lateral low rigidity sections, thestretchable sheet is provided to be superposed on the side region in thewidth direction.
 5. The absorbent article according to claim 4, whereinin the wearing mode of the absorbent article, the side region is bent sothat an end of an outer side in the width direction of the side regionis raised in the thickness direction of the absorbent body, and thecenter region is bent so that an end of an inner side in the widthdirection of the center region is raised in the thickness direction, theabsorbent body is consequently deformed to have a W-letter shaped crosssection in the width direction of the center absorbing section.
 6. Theabsorbent article according to claim 1, wherein the cover sheet at thenon-skin-contacting face of absorbent core is not directly joined to amember located at the non-skin-contacting face of the cover sheet, in acenter portion in the width direction of the absorbent core.
 7. Anabsorbent article having a width and a length orthogonal to the width,comprising: a chassis having at least a front torso surrounding regionand a rear torso surrounding region arranged along a longitudinaldirection of the absorbent article; a crotch region positioned betweenthe front torso surrounding region and the rear torso surrounding regionin the chassis; an oblong absorbent body provided extending from thefront torso surrounding region to the rear torso surrounding regionalong the longitudinal direction, the absorbent body comprising anabsorbent core covered with a cover sheet, a pair of stretchable sheetsarranged at both outer side edges of the cover sheet with respect to thewidth direction and extending in the longitudinal direction, an outeredge of each of the stretchable sheets being formed to have an archportion that recesses toward a center line of the absorbent body at acenter portion in the longitudinal direction of the stretchable sheets;a torso opening section formed at one side when in a wearing mode; apair of leg openings formed at another side when in the wearing mode; askin-contacting face facing an inner face when in the wearing mode; anot-skin-contacting face facing an outer face when in the wearing mode;and an elastic member arranged along a side edge extending in alongitudinal direction of the crotch region constituting the legopening, wherein the absorbent core includes: a first narrow widthsection; a second narrow width section arranged longitudinally spacedfrom the first narrow width section; a center low rigidity sectionformed along a center line that halves the absorbent article in thewidth direction of the absorbent article; and a pair of lateral lowrigidity sections provided at both sides of the center low rigiditysection in the width direction of the absorbent article with asubstantially equal interval; wherein the cover sheet has at a skincontacting side a length in the width direction that is longer than alength of the absorbent core in the width direction so that the coversheet at the skin contacting side is loosened, and at the skincontacting side, the cover sheet is entirely free of joining with theabsorbent core from one end to another end in the width direction of theabsorbent core, and the stretchable sheet has a narrowest width at thearch portion, and a portion of the stretchable sheet that has thenarrowest width at the arch portion extends outward over the outer sideedge of the cover sheet at the arch portion, and an outer edge of thestretchable sheet, including the arch portion, extends over the outerside edge of the cover sheet along the longitudinal direction of thestretchable sheet.